Recently, there have been made great advancements in production of miniature and light-weight electronic apparatuses such as mobile telephones and personal computers. In accordance therewith, such apparatuses having a movable housing arranged to be opened and closed with respect to a fixed housing, i.e., folding type apparatuses, are increasing in number. A folding device used for those apparatuses is required to be low in cost and easy to use. A folding device having such structure mentioned just above is disclosed in Japanese Laid-open Patent Publication No. 2002-89542.
A conventional folding device will be described below with reference to FIG. 4 to FIG. 6.
In a sectional view of the drawings, the dimension is shown elongated in the radial direction to facilitate the understanding of the relationship between a fixed cam and a movable cam.
FIG. 5 and FIG. 6 are a sectional view and an exploded view in perspective of a conventional folding device.
Metal fixed member 1 in a substantially cylindrical shape is formed with fixed portion 1A on its left-hand side face and provided with fixed cam 2 on a periphery of its right-hand side face. Fixed cam 2 comprises protruded portion 2A and two sloped portions 2B and 2C extended from protruded portion 2A toward the left and right.
Further, metal movable member 3, which is also in a substantially cylindrical shape, is arranged for rotation in an opening and closing direction with respect to fixed member 1. Movable member 3 is provided with movable cam 4 on a periphery of its left-hand side face in confronting relation with fixed cam 2.
Movable case 5, which is in a substantially cylindrical shape and made of sintered alloy, is provided with wall portion 5A sticking outward on its outer periphery and groove portion 5B on its inner periphery.
Protrusion 3A provided on the outer periphery of movable member 3 is inserted into groove portion 5B so that movable member 3 is movable in an axial direction.
Further, coil spring 6 is mounted so as to be weakly pre-compressed in a space between a right-hand side face of movable member 3 and a right-hand bottom face of movable case 5. Spring 6 urges movable member 3 leftward, and thereby, a tip end of movable cam 4 is held in resilient contact with sloped portion 2B of fixed cam 2.
Fixed member 1 is fixed to a left end portion of fixed shaft 7 in a substantially circular pillar shape.
Moreover, a right end portion of fixed shaft 7 passes through a hollowed portion of movable member 3 and spring 6 to be rotatably mounted to a right-hand face of movable case 5 by means of locking ring 8. Fixed portion 1A of fixed member 1 rotatably sticks out of the left-hand side face of movable case 5. Folding device 10 is thus constructed with fixed member 1, movable member 3, spring 6 and the like housed in movable case 5.
Fixed portion 1A of fixed member 1 of folding device 10 is fixed to fixed housing 22 while wall portion 5A of movable case 5 is fixed to movable housing 23, respectively, as shown in the perspective view of a mobile telephone of FIG. 4, for example. On the upper side of fixed housing 22, there are formed operating portion 22A made up of a plurality of keys and voice input portion 22B made up of members such as a microphone. Display portion 23A formed of an LCD and the like and voice output portion 23B formed of a speaker and the like are formed on a surface of movable member 5.
An arrow in FIG. 4 shows an opening and closing operation of movable housing 23.
Thus, the electronic apparatus is constructed by having movable housing 23 hingedly supported by folding device 10 for opening and closing with respect to fixed housing 22.
In the above structure, spring 6 urges movable member 3 downward, that is, in a closing direction when the tip end of movable cam 4 is in resilient contact with sloped portion 2B provided on the lower part of fixed cam 2, as shown in FIG. 5. Accordingly, movable housing 23 to which movable case 5 is fixed is held to be closed with respect to fixed housing 22.
In such a closing state, when movable housing 23 is opened by means of a hand, movable member 3 having protrusion 3A inserted in groove portion 5B moves toward the right in movable case 5 and rotates upward through movable case 5 fixed to movable housing 23. The tip end of movable cam 4 is then in resilient contact with upper sloped portion 2C over protruded portion 2A of fixed cam 2, so that movable member 3 is urged upward, that is, in an opening direction. Movable housing 23 is thus opened.
That is to say, rotation of movable case 5 fixed to movable housing 23 allows movable member 3 to move in the axial direction, so that the tip end of movable cam 4 would be in resilient contact with any one of sloped portions 2B and 2C of fixed cam 2.
An opening and closing operation of movable housing 23 with respect to fixed housing 22 is arranged as described above.
The opening and closing operation is carried out by holding movable cam 4 in resilient sliding contact with fixed cam 2. Therefore, fixed member 1 and movable member 3 require predetermined hardness and strength in order to prevent the cams from being worn and broken due to the opening and closing operation. Accordingly, metal such as steel or copper alloy is generally used for the above.
Movable case 5 should be formed with wall portion 5A for fixing movable case 5 to movable housing 23 and groove portion 5B for holding movable member 3 for movement in an axial direction. The shape of the above is limited so much that production of parts is difficult in pressing. Metal powder of such as iron or copper alloy is thus mixed with resin powder for sintering or the sintered material is cut so as to form movable case 5.
In the conventional folding device, however, forming movable case 5 from sintered metal powder or the like causes a problem that the number of processes for processing parts is increased, so that the folding device would be expensive.
Moreover, the conventional folding device has the problem that high precision production of thin-walled part is needed.
The invention aims to solve such conventional problems and to provide a folding device capable of easy processing of parts and lowering of cost.